DE1570623B2 - Process for the production of spinnable solutions of polyacrylonitrile and its copolymers - Google Patents

Description

There has now been a process for the preparation of spinnable solutions of polyacrylonitrile and its copolymers with at least 50% acrylonitrile components through solution polymerization of acrylonitrile alone or together with other monomers at elevated temperatures in organic solvents with the help of catalysts in the presence of strong organic or inorganic acids and / or an aromatic disulfonimide, optionally together with small amounts of primary or secondary amines or aminosulfonic acids, which is characterized in that an organic sulfinamide of the general formula as a catalyst

, R '

R "

R — s — n:

Benzenesulfinamide

p-Toluenesulfinamide

p-chlorobenzenesulfinamide

N, N-dimethyl-benzenesulfinamide

N, N-dimethyl toluenesulfinamide

Ν, Ν-methylphenylbenzenesulfinamide

Ν, Ν-diethyl-p-chlorobenzenesulfinamide wherein R is an aliphatic or aromatic radical, which is halogen, alkyl, alkoxy, Aryl may contain, R 'and R "are hydrogen, a lower alkyl radical or aryl radical, or both together

5 with N denote a heterocyclic radical, optionally together with an organic peroxide, is used.

This solution polymerization also takes place in the low temperature range between 15 and 35 ° C

ίο at high speed and easily reproducible.

The resulting viscous spinnable solutions are colorless or only very slightly discolored, clear, gel-free and stable against discoloration and gelation.

Because of their ease of manufacture, good durability

15 and solubility in the reaction medium, further because of their high activity are preferred aromatic sulfinamides, such as benzene and substituted benzenesulfamides, are used. It be for example the following sulfinamides

ao names:

Fp:

C ₆ H ₅ - SO - NH ₂

CH ₃ - C ₆ H ₄ - SO - NH ₂

Cl - C ₆ H ₄ - SO - NH ₂

C _R H _R - SO

CH ₃

CH ₃

121 ° C 120 ° C 127 ° C

(Oil) b.p .: 567553

CH ₃

: CH ₃ -C ₆ H ₄ -SO-N ^ ^ 52-53 ⁰ C

CH ₃

CH ₃
: C ₆ H ₅ -SO-N ^

C ₆ H ₅

/ -C ₂ H ₅
: Cl-C ₆ H ₄ -SO-N ^

C ₂ H ₅

Benzenesulfinic acid morpholide

p-Toluenesulfinic acid morpholide

p-Chlorobenzenesulfinic acid morpholide

Benzenesulfinic acid piperidide

p-chlorobenzenesulfinic acid piperidide

N, N-dimethyl- / S-naphthalenesulfinic acid amide

Methanesulfinic anilide

Methanesulfinic acid p-toluidide

The compounds mentioned can analogously to those in the literature for benzene and Toluo.lsulfinamide (B r a u η u. K a i s e r, B. 56 553), or for methane-C.H, —SO —N

CH ₃ - C ₆ H ₄ - SO -

Cl - C _e H _B - SO - N

CH _B - SO

75 ° C

128 ⁰ C

137 ° C

114 to 116 ° C

137 ° C

CH ₃

CH ₃ - SO - HN - C ₆ H ₅

CH ₃ - SO - HN - C ₆ H ₄ - CH ₃

86 to 88 ⁰ C 103 ⁰ C

sulfinic anilide and toluidide (J. org. Chem. 23.1958, P. 805 to 807) described methods.

Organic peroxides are advantageously organic-saturated copolymerizable compounds, such as meniche Hydroperoxides, such as tert-butyl hydroperoxide, thacrylonitrile, acrylic or methacrylic acid esters or or cumene hydroperoxide, ketoperoxides, such as cyclo-amides, styrene and its derivatives, vinyl chloride or hexanone peroxide, methyl ethyl or methyl isobutyl vinylidene chloride carried out. If you polymerize z. B. ketone peroxide, acyl peroxides such as lauroyl peroxide, 5 1 to 10 preferably, 5 to 7 percent by weight of one Diacetyl peroxide, benzoyl or 2,4-dichlorobenzene, acrylic or methacrylic acid ester, a vinyl ester peroxide, also perester, such as tert-butyl perbenzoate, or a styrene derivative together with acrylonitrile, tert-butyl diperphthalate, tert-butyl perlaurinate, tert- increases the solubility of the polymers formed Butyl peracetate, mono-tert-butylpermaleate, tert-in the reaction medium considerably. This is how it is Butyl peroctoate, tert-butyl perisobutyrate or tert-io possible to use higher initial concentrations Butyl perpivalate, is used. and correspondingly higher reaction speeds,

Hydrochloric acid, molecular weights and polymer concentrations can be used as strong inorganic acids Phosphoric acid, preferably sulfuric acid, and when in solution. In addition, the strong organic acids, aromatic sulfonic acids, threads from the copolymers mentioned, too such as benzene or toluenesulphonic acid, tetralinsulphon- 15 easier to dye. To be able to color with deep acid, isopropyl or diisopropylbenzenesulfonic acid, color shades can be achieved further Oxalic acid, and preferably aromatic mers with acidic or basic groups, such as sulfo-disulfonimides with the general formula styrene, methacrylaminobenzene-benzene-disulfimide or

Polymerize vinyl pyridine.

R - SO ₂ - NH - SO ₂ - R ', 20 The aim is to produce threads

Acrylonitrile copolymers or fibers with special

such as benzene or toluene disulfonimide can be used. Fish properties are usually mixed in. Dimethylformamide, both organic and components, can be used in larger quantities. Copoly inorganic acids can also be used, whereas acrylonitrile is merized ζ. B. with 20 to 50 weight in dimethyl sulfoxide and dimethylacetamide 25 percent vinylidene chloride, very highly concentrated spinning solutions can be obtained in the catalyst system peroxide / sulfinamide and the advantageous organic acids are used. Instead of threads spun from it, the acids mentioned can also have unsaturated, set flammability and combustibility,
copolymerizable aromatic disulfonimides depending on which solvent or which

Contain free, strongly acidic groups, such as methacrylic 30 mixing components and in what proportion to the aminobenzene-benzene-disulfonimide can be used. Acrylonitrile can be used, the ratio Also a combination of the acidic ratio mentioned between the amount of monomer and the amount of solvent in the bindings can apply. Reaction mixture varied within broad limits

An acceleration of the polymerization when ver:

Use of the Catalyst Systems According to the Invention 35 Acrylonitrile is polymerized in dimethylformamide can by adding small amounts of primary alone, it is necessary to increase the monomer concentration or secondary amines can be achieved. Keep respect- tration below 25 percent by weight, if one lent the discoloration of the spinning solutions at higher levels of clear, non-gelled solutions. If the Temperatures have aminosulfonic acids such as polymerization of acrylonitrile together with z. B. Taurine, N-methyltaurine, sulfanilic acid or N-methyl-40 5 to 8 percent by weight of methyl acrylate, vinylsulfanilic acid If acetate or styrene is used particularly favorably as an accelerator, the initial mono can be shown. concentration up to about 40 percent by weight,

The known presence of smaller amounts of water, preferably between 25 and 35 percent by weight, in the reaction medium has one on the polymerization without gelling or clouding of the beneficial effect: the reaction rate 45 solution during or after the termination of the polymeri increased and at the same speeds - im sation occurs. In the case of copolymerization of acrylic comparison to anhydrous approaches ■ - · a nitrile with about 25 to 45% vinylidene chloride can be carried out Molecular weight increase. Monomer concentration in dimethylformamide.

The polymerization reaction will be approximately 30 to 60 percent by weight of this. on The oxygen in the air does not dissolve in the reaction mixture. The reason for the poor dissolving properties is the disturbs; but it is when using the catalyst limits the initial monomer concentration systems peroxide / sulfinamide / acid are advantageous, dimethylacetamide and dimethylsulfoxide for example Polymerization in a closed reaction - 5 to 10 percent by weight lower than with the digester under a slight protective gas pressure (e.g. methylformamide. The reaction mixture that is used for Nitrogen) is used to allow access to further polymerization, contains oxygen in the case of the kata to prevent amounts during the reaction. lysator combination sulfinamide / acid each up to It can also be monomers, the stabilizers ■ - such as 3 percent by weight, preferably 0.2 to 2 Ge-thiosemicarbazide, Ammonia, hydroquinone or percent by weight of the compounds mentioned. The MoI-whose Derivatives - contain, without purification, the ratio of sulfinamide to acid can be advantageous. 60 adhesive in the range from 1: 0.2 to 1: 4. When using

As solvents in which the polymerization of the peroxide / sulfinic acid catalyst system is carried out is increased, dimethyl amide / acid are preferably used up to 2 percent by weight, formamide, dimethylacetamide and dimethyl sulfoxide are preferably 0.05 to 0.5 percent by weight of the grain used. However, other components for acrylonitrile can also be used. The molar ratio between polymers and copolymers known organic peroxide and sulfinamide can preferably niche solvents can be used. between 1: 0.2 and 1: 8, the acidity should be up to

The solution polymerization of a 4-fold molar excess to the sulfinic acid-acrylonitrile is preferred be used in the presence of other olefinic-unamides.

The polymerization temperature can because of the high activity of the catalyst systems according to the invention can be selected in a wide range between 0 and 80 ° C. Preferably the polymerization started in the vicinity of the respective room temperature in the range of 15 to 35 ° C. It then depends on the intensity of the cooling, whether and how high the reaction temperature due to the exothermic Heat of reaction will increase during the polymerization. In dimethylformamide or dimethylacetamide solution 50 to 80% yields of polymers can be achieved in 5 to 20 hours and in dimethyl sulfoxide solution can be achieved in 3 to 10 hours, with polymers suitable for fiber production Molecular weights, preferably measured with relative viscosities from about 1.75 to 2.0 in a 0.5% dimethylformamide solution at 20 ° C (corresponds to Fikentscher's K values of around 75 to 85).

After the desired conversion or solution concentration has been reached, a known polymerization inhibitor is used or / and strong acid stirred into the solution. This can avoid that low molecular weight polymers are formed during further processing of the solution. Then can the solution directly or after removal of the unreacted monomers - z. B. in a thin film evaporator under reduced pressure - spun by known dry or wet spinning processes will.

The spinning solutions produced by the process according to the invention are colorless or only slightly yellowish discoloration, clear and gel-free, which ensures easy, unproblematic further processing is. After removing the unreacted monomers, they can be stored for a long time without that the viscosity of the solutions changes significantly. The threads that are spun have a high Whiteness, good thermal stability and excellent textile values.

The main advantage of the process is that the polymerization takes place at a high rate can be carried out at a low temperature. This makes it possible to be particularly temperature-sensitive Acrylonitrile copolymers, such as copolymers containing vinyl or vinylidene chloride or copolymers with basic mixed components, with significantly improved quality (degree of whiteness, Thermostability, etc.). In addition, there is the possibility of the polymerization at Carry out room temperature, whereby the reaction, the process technology and the apparatus Effort - especially on a semi-technical and industrial scale - much simplified and so the whole process can be made cheaper.

example 1

In 75 g of dimethyl sulfoxide, 23.5 g of acrylonitrile, 1.5 g of methyl acrylate and 0.35 g of benzene sulfamic acid amide were added and 0.2 g conc. Dissolved sulfuric acid. The reaction mixture was covered in a watch glass Leave Erlenmeyer flask at room temperature (22 to 24 ° C). After a reaction time of 8 hours the result was a light yellow, clear, viscous solution with a polymer concentration of 18.2% (corresponds to 73% yield). The polymer had a relative viscosity of 1.73 (K value 74.8).

, Example2

The same reaction components as in Example 1 were dissolved in 75 g of dimethylacetamide and polymerized in the same way at room temperature for 20 hours. The yield was 64.8% and the? 7rei · of the polymer was 1.63 (K value 70.2). The viscous solution was discolored pale yellow.

Example 3

A reaction mixture - consisting of 65 g of dimethylformamide, 32.8 g of acrylonitrile, 2.2 g of methyl acrylate, 1.0 g methacroylaminobenzene-benzene-disulfimide and 0.4 g of benzenesulfinamide - was polymerized as described in Example 1 for 20 hours. The resulting pale, clear solution contained 21.4% polymer with a rel. Viscosity of 1.70. The films cast from the solution were deeply stainable with basic dyes and with one They were only slightly yellowed by tempering at 160 ° C. for one hour.

Table 1

Peroxide Sulfine Organic acid G water sales 1.71 Appearance attempt acid- Surname the solution No. G amide 0.3 G % 2.06 0.28 G p-isopropylbenzene 78.4 clear, weak 1. 0.195 sulfonic acid 0.3 1.72 yellow 0.32 p-isopropylbenzene 0.6 64.0 clear, colorless 2. 0.225 sulfonic acid 0.3 1.76 0.28 Diisopropylbenzene - 75.6 clear, light yellow 3. 0.195 sulfonic acid 0.3 1.73 0.28 Diisooronylbenzene 0.6 72.0 1.72 clear, almost colorless 4th 0.195 sulfonic acid 0.3 1.87 0.30 Tetralin sulfonic acid 0.3 - 69.4 clear, light yellow 5. 0.30 0.21. Tetralin sulfonic acid 0.6 0.6 71.4 clear, almost colorless 6th 0.38 0.21 Metbacro) lamino- - 67.6 1.85 clear, colorless 7th 0.265 benzene-benzene-di- sulfimide 0.6 0.38 Methacroylamino 0.6 70.3 clear, colorless 8th. 0.265 benzene-benzene-di- sulfimide

409 544/356

ίο

Example 4

In this series of experiments, 100 ml long-necked flasks with a ground-joint cap were used as the reaction vessel. The reaction mixtures each contained 75 g of dimethyl sulfoxide, 23.5 g of acrylonitrile, 1.5 g of methyl acrylate, and also mono-tert-butylpermaleate (50% solution in dimethyl phthalate), benzenesulfinamide, an organic acid and possibly water. The fully filled and closed reaction vessels were placed in a water bath at 25 ^° C. After a reaction time of 4 hours, the viscous solutions formed were precipitated in a water-methanol mixture. The yields, the rel. Viscosities of the polymers and the appearance of the solutions, and also the amount of catalyst, acid and water used, are given in Table 1 above.

Example 5

At 15 ° C, the monomer mixture was dissolved in dimethyl sulfoxide, as described in Example 4, with 0.42 g of mono-tert-butylpermaleate (50% solution), 0.29 g Benzene sulfamic acid amide and 0.6 g methacroylaminobenzene disulfimide Polymerized for 6 hours. The yield was 71% and the relative viscosity 2.12. The viscous solution obtained was completely colorless.

Example 6

65 g of dimethylformamide, 2.1 g of methyl acrylate, 32.9 g of acrylonitrile, 0.42 g of mono-tert-butylpermaleate (50% solution), 0.29 g of benzenesulfinamide and 0.1 g of conc. Sulfuric acid were heated at 15 ^° C., as in Example 4, for 10 hours. A colorless, viscous solution with a polymer concentration of 25.5% (yield: 73%) was formed. The rel. The viscosity of the polymer was 1.82.

Example7

In order to show the effectiveness of the catalyst systems with various sulfonic acid amides, the the following series of experiments carried out: The reaction mixture consisted in all cases of 65 g of dimethylformamide, 32.9 g acrylonitrile, 2.1 g methyl acrylate, 0.3 g mono-tert.-butylpermaleate (50% solution) 0.3 g sulfamic acid and 0.2 g conc. Sulfuric acid. The reaction was carried out at 35 ° C and lasted 4 hours. Table 2 below contains the test results and the names of those used Sulfenic acid amides:

IO attempt
Ni. 15th 2. 20th 4th 30th Table 2 sales
% η «Λ. Color of
solution 1. Sulfinamide 76.0 1.54 weak Benzenesulfine yellow 3. acid amide 60.3 1.72 colorless 5. p-toluene zolsulfinic acid 6th amide 63.0 1.68 colorless p-chlorobenzene sulfinic acid amide 68.8 1.63 colorless N, N-Dime ethyltoluene sulfinic acid amide 66.3 1.65 colorless Benzenesulfine acid mor-
pholid
p-toluene 56.7 1.78 almost colorless sulfinic acid morpholide

Example 8

In the following examples, further catalyst combinations were made from various peroxides and sulfinamides are used. The reaction mixture, the amounts of catalyst and acid and the reaction conditions were as in the example 7. The reaction time: 6 hours. The results and the catalyst combinations are in Table 3 summarized:

Table 3

attempt
No. Peroxide Sulfinamide sales
% V rel. Color of the solution 1. Lauroyl peroxide N, N-dimethyltoluene 63.3 1.91 pale yellow sulfinamide 2. Lauroyl peroxide Benzenesulfinic acid morpho-
lirl 64.0 1.82 almost colorless 3. Lauroyl peroxide JUU
p-toluenesulfinic acid 61.2 1.87 almost colorless morpholide 4th Methyl ethyl ketone peroxide Ν, Ν-dimethyltoluenesulfine 59.6 1.90 pale yellow (50% solution) acid amide 5. Methyl ethyl ketone peroxide Benzenesulfinic acid 58.0 1.83 colorless (50% solution) morpholide 6th Methyl ethyl ketone peroxide p-toluenesulfinic acid 55.7 1.79 colorless (50% solution) morpholide

Example 9, 0.35 g of mono-tert-butylpermaleate (50% solution),

0.24 g benzenesulfinamide, 1.2 g methacroylamino

In a pressure-tight, closed reaction vessel 65 benzene-benzene-disulfimide and 0.1 g of conc. Sulfur out Glass became the following: reaction mixture under acid. After 16 hours an almost colorless, Nitrogen polymerized at 25 ° C: 50 g of dimethyl-viscous solution with. 37% polymer concentration (Ausformamid, 30 g acrylonitrile, 20 g vinylidene chloride, yield 74%). The polymer had a rel. viscosity

11 12

of 1.84, a chlorine content of 28.3 percent by weight, the reaction was stopped by adding an inhibitor was flame-retardant and the films from it were also stopped and the 27% light, clear polymer base Dyes can be easily dyed, solution (conversion: 77%) with dimethylformamide

24% diluted. Subsequently, the non-enveloped

For example, 0 5 residues of monomers are deposited by thin-film distillation

removed from solution under reduced pressure.

As in Example 9, a reaction mixture was made from The solution was 28.8% strength after the distillation and 50 g of dimethylformamide, 32.5 g of acrylonitrile, 17.5 g of vinyl was able to produce white denchloride, 0.33 g of mono- tert-butylpermaleate, 0.23 g of thermally stable threads with good textile properties Benzolsulfhisäureamid, 0.15 g of conc. Sulfuric acid, io to be spun. The threads could also be dyed in deep shades with basic 0.3 g of taurine and 0.6 g of water for polymerization. The scheduled. At 25 ° C after 16 hours a rel. The viscosity of the polymer was 1.80.
light yellowish 41.7% polymer solution (yield:

83.4%,? 7rei: 2.11). Example 13 had the highly concentrated solution

excellent thread pulling power. The poly- 15

mere contained 24.3 percent by weight chlorine and had In the same reaction vessel and on the same

a greatly reduced flammability. As described in Example 12, 54 kg of Di

methylformamide, 29.5 kg acrylonitrile, 16.5 kg vinyli-

Example 11 Denchloride, 230 g butyl permaleate (50%), 160 g

ao benzenesulfinamide, 200 g of toluene disulfimide and

In a with thermometer, vacuum and stick 52 g conc. Sulfuric acid polymerizes. After a double-walled reaction time of 20 hours, the temperature rose in the V4A stirred autoclave, the reaction mixture was in the solution to 37 ° C and an almost color-6.5 kg dimethylformamide, 3.29 kg acrylonitrile, 210 g loose , clear, viscous solution. The polymer concentration methyl acrylate, 9.5 g of mono-tert-butyl permeation was 32.6%, the yield 70.8% and the rel. inat (= 19 g, 50% solution in dimethyl phthalate), viscosity of the polymer 1.76 (K value: 76). The 16 g of benzenesulfinic acid morpholide and 15 g of conc. Solution was diluted to 28%, distilled and closed with sulfuric acid under 0.5 atm. Nitrogen protective pressure with a concentration of 37% after which it was stirred for 20 hours. The temperature of the solution is spun in the dry spinning process. A sample from was kept between 30-30 of the highly concentrated, distilled solution and 35 ° C. with the aid of an automatic control system. It was almost colorless and stored at room temperature for 30 days. While clear, viscous solution with a polymer content of this time did not change its viscosity.
25.6% (yield: 73%), after the addition of a polymerization inhibitor according to a known dry example 14
spinning process was spun. The polymer 35

had a rel. Viscosity of 1.87 (K value: 81.3). As indicated in Example 12, the following became

Approach polymerized; 52 kg dimethylformamide, 28.8 kg

Example 12 Acrylonitrile, 19.2kg vinylidene chloride, 1.4kg metha-

croylaminobenzene-benzene-disulfimide, 700 g water,

A 2001 Ruhr autoclave 40 240 g butyl permaleate (50%) and 185 g p-toluene was used as the reaction vessel. equipped as in Example 11 - used. Of sulfinamide. The temperature rose during the the boiler jacket was only a cooling water line polymerizing to 42 ° C. Polymerization time: connected. The reaction mixture contained 65 kg for 16 hours. Solution concentration: 36%; Sales: Dimethylformamide, 32.7 kg acrylonitrile, 2.3 kg acrylic 73%; K value: 81.4 The pale yellow, clear solution acid methyl ester, 800 g methacroylaminobenzene-di- 45 was immediately after the interruption (inhibitor) sulfimide, 290 g of 50% mono-tert-butylpermaleate, the polymerization by the dry spinning process 200 g of benzenesulfinamide and 55 g of conc. Sulfur spun. The threads were - compared to chloric acid. After filling in the components (nitrogen-containing acrylonitrile copolymers, which on atmosphere) the polymerisation started already in the conventional way (aqueous polymerisation) Room temperature. When the temperature was established through the 50 - supremely white and thermoexothermic Heat of reaction rose to 30 ° C became stable. You could use basic dyes in deep the cooling switched on. In the course of the polymer tones are dyed, had good textile values and Then the temperature rose gradually - despite a greatly reduced flammability (chlorine content: intensive stirring - up to 38 ° C. After 20 hours 27.7 percent by weight).

Claims (2)

I 2 and / or hydrolytic decomposition of the solvent Patent claims: or the catalysts or other additives 1. Process for the production of spinnable stand can - caused. These reactions dissolve polyacrylonitrile and its mixtures, however, usually run at considerable speed with at least 50% acrylonitrile 5 only above 40 to 50 ° C. With longer polymer contents by solution polymerisation of acrylation time, but especially with high polymerinitrile Alone or together with other monotization temperatures therefore inevitably arise at elevated temperatures in organic colored solutions or inferior in practice Solvents with the help of catalysts in end products. Hence, it is an important requirement Presence of strong organic or inorga- io the catalysts used oppose that they nical acids and / or an aromatic one even at low temperatures in small amounts Disulfonimide, optionally together with high polymerization rates, d. H. height wrestling amounts of primary or secondary yields with the shortest possible reaction times, Amines or aminosulfonic acids, thereby make it possible. It is also necessary that they characterized in that a 15 is completely soluble in the reaction medium as a catalyst and organic sulfinamide of the general formula remain in solution even during the course of the polymerization, •, because undissolved catalyst residues or failed / Salts or decomposition products increase the gelation R - S - N \ tendency and make further processing more difficult. II \ η "20 With the previously known methods, all could O these demands are by no means fulfilled simultaneously and completely. As catalysts for where R is an aliphatic or aromatic solution to the solution polymerization of acrylonitrile Remainder, which as further substituents halogen, alkyl, in organic solvents were boron trifluoride, Can contain alkoxy, aryl, R 'and R "water, azo compounds, inorganic and organic hydrogen, a lower alkyl radical or aryl radical, or oxides or toluenesulfinic acid sodium salt is used, both together with N a heterocyclic radical It has been shown here that either the expressions optionally together with a booty of polymers and the molecular organic compounds achieved Peroxide, is used. weights were not high enough (boron trifluoride) 2. The method according to claim 1, characterized in that 30 or high reaction temperatures or long range that the polymerization at temperatures action times were necessary (azo compounds and pervon 15 to 35 ° C is carried out. oxides alone) in order to create technically usable products to be able to aim. The high reaction temperatures called for peroxides - especially in dimethyl- There are already numerous processes for the production of formamide solution - particularly easily unwanted spinnable solutions of acrylonitrile polymers discoloration of the solutions. When using and copolymers by polymerization in azo catalysts, the atmospheric oxygen must be described because of organic solvents. Since its inhibiting effect was completely excluded, the advantages of this process were also fully explained, and for the same reason reference can also be made to the processes containing polymerization stabilizers (inhibitors) that have hitherto been customary on an industrial scale, where the polymerization in the monomer is not used directly ; they have to be carried out in an aqueous medium and the poly- previously - mostly by distillation - removed merisate isolated, dried, crushed and again, which means that the process has to be resolved with additional burdens if one becomes too spinnable. When using inorganic pearl solutions I want to get there. The advantages of solution poly- 45 oxides or alkali salts of sulfinic acids are merization processes but can only be made particularly unpleasant if the resulting spinning solubility of these compounds in the reaction medium is solutions or the threads spun from them the fact that during preparation and during the correct quality requirements correspond to: The spinning polymerization must dissolve considerable salt precipitates, especially for the spinning technique, which either not at all or only dissolved at very high required, high viscosities or polymer concentration temperatures can be. This will have trations, the molecular weight of the spinning ability and durability of the spinning solution polymers must be in the range that is significantly reduced for the. Fiber production is suitable as a redox catalyst system. For a good quality, peroxides in dimethylsulfoxide solution are also required that the spinning solutions light formamidinesulfinic acid are used, but also here, as - as colorless as possible or only slightly discolored, with the other catalysts mentioned, could be clear - free of undissolved solid substances or gel under 40 no sufficient particles to 5O ⁰ C for practical applications - are achieved and stable to discoloration and gelation high polymerization rates. will. The requirement of the indispensable for fiber purposes, 60 From the Austrian patent specification 236 642 is relatively high molecular weights makes known to use acrylonitrile polymers the organic solvents with high chain of dimethyl sulfoxide as the medium and azo-bis- transfer constants, especially in the case of dimethyl bonds as a catalyst, with the formamide, long reaction times necessary. Reaction system before the start of the polymerization It is known that acrylonitrile polymers react at least one or more inorganic ones especially in solution, discolor very easily. The incorporated and / or organic acids are incorporated. For Coloring is done by auto-oxidation reactions and this procedure, however, apply the above of nucleophilic reagents - caused by thermal disadvantages.